U.S. patent number 4,664,280 [Application Number 06/814,068] was granted by the patent office on 1987-05-12 for composite closure.
This patent grant is currently assigned to H-C Industries, Inc.. Invention is credited to Daniel G. Denman, John R. Schetzsle, Ralph H. Whitney, Sheldon L. Wilde.
United States Patent |
4,664,280 |
Whitney , et al. |
May 12, 1987 |
Composite closure
Abstract
A composite closure for a container is disclosed which includes
an outer plastic cap and an inner plastic sealing liner. Formation
and retention of the sealing liner within the cap is promoted by
the provision of an annular liner-retaining lip which extends
inwardly from a skirt portion of a cap in closely spaced relation
to its top wall portion, and thus defines an annular recess
therewith, Liner retention is further enhanced by the provision of
a plurality of circumferentially spaced first liner-engaging
projections which are arranged in adjacent pairs within the annular
recess of the cap in converging relation with each other. Liner
retention is further enhanced by the preferred provision of a
plurality of second circumferentially spaced liner-engaging
projections extending integrally from the top wall portion of the
cap in operative association with the converging adjacent pairs of
the first projections.
Inventors: |
Whitney; Ralph H.
(Crawfordsville, IN), Wilde; Sheldon L. (Crawfordsville,
IN), Schetzsle; John R. (Crawfordsville, IN), Denman;
Daniel G. (Crawfordsville, IN) |
Assignee: |
H-C Industries, Inc.
(Crawfordsville, IN)
|
Family
ID: |
27110881 |
Appl.
No.: |
06/814,068 |
Filed: |
December 20, 1985 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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723858 |
Apr 16, 1985 |
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Current U.S.
Class: |
215/350 |
Current CPC
Class: |
B65D
41/3423 (20130101); B65D 41/045 (20130101) |
Current International
Class: |
B65D
41/04 (20060101); B65D 41/34 (20060101); B65D
053/04 () |
Field of
Search: |
;215/350 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Scale representation of plastic closure having outer shell and
liner adjacent top wall of shell, partially cutaway; 1 page, FIGS.
1 and 2..
|
Primary Examiner: Norton; Donald F.
Attorney, Agent or Firm: Dressler, Goldsmith, Shore, Sutker
& Milnamow, Ltd.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
The present application is a continuation-in-part of application
Ser. No. 723,858, filed Apr. 16, 1985, now abandoned.
Claims
What is claimed is:
1. A composite closure, comprising:
a plastic cap having a top wall portion, a depending annular skirt
portion, and an annular liner-retaining lip extending inwardly of
said skirt portion in spaced relation to said top wall portion to
define an annular recess therewith; and
a plastic sealing liner positioned adjacent said top wall
portion,
said plastic cap including a plurality of circumferentially spaced
liner-engaging projections in engagement with said sealing liner,
said projections being positioned at least partially within said
annular recess and extending integrally from the junction of said
annular lip and said top wall portion inwardly of said closure, all
of said liner-engaging projections being arranged in adjacent
pairs, wherein the projections of each said adjacent pair are
arranged in converging relation to each other to retain an edge
portion of said sealing liner therebetween.
2. A composite closure in accordance with claim 1, wherein
said adjacent pairs of projections comprise first liner-engaging
projections, said plastic cap including a plurality of
circumferentially spaced, second liner-engaging projections
extending integrally from said top wall portion in operative
association with said adjacent pairs of first projections for
retaining and sealing liner in position within said plastic
cap.
3. A composite closure in accordance with claim 2, wherein
one of said second liner-engaging projections is positioned in
closely spaced relation to and generally circumferentially
intermediate of each said adjacent pair of said first
projections.
4. A composite closure in accordance with claim 1, wherein
each said adjacent pair of liner-engaging projections converge at
an obtuse angle with respect to each other.
5. A composite closure in accordance with claim 1, wherein
each said liner-engaging projection is arranged in diverging
relation to the adjacent liner-engaging projection of the
immediately adjacent converging pair of said projections.
6. A composite closure in accordance with claim 1, wherein
each said liner-engaging projection extends non-radially inwardly
of said plastic cap.
7. A composite closure in accordance with claim 1, wherein
each said liner-engaging projection extends vertically between
generally opposed surfaces of said top wall portion and said
liner-retaining lip.
8. A composite closure in accordance with claim 1, wherein
each said liner-engaging projection has a free edge spaced from and
generally facing a surface of said liner-retaining lip which said
lip surface is generally opposed to said top wall portion.
9. A composite closure in accordance with claim 1, wherein
each said liner-engaging projection is substantially detached from
said liner-retaining lip.
10. A composite closure, comprising:
a plastic cap having a top wall portion, and a depending annular
skirt portion having an internal thread formation, and an annular
liner-retaining lip extending inwardly of said skirt portion in
spaced relation to said top wall portion to define an annular
recess therewith; and
a plastic sealing liner positioned adjacent said top wall
portion,
said plastic cap including a plurality of circumferentially spaced
first liner-engaging projections, said projections being positioned
at least partially within said annular recess and extending
integrally inwardly from the junction of said annular lip and said
top wall portion, said first projections being arranged in adjacent
pairs, wherein the projections of each said adjacent pair are
arranged in converging relation to each other to retain an edge
portion of said sealing liner therebetween,
said plastic cap including a plurality of second liner-engaging
projections extending integrally from said top wall portion in
operative association with said adjacent pairs of first
liner-engaging projections for retaining said sealing liner in
position within said plastic cap.
11. A composite closure in accordance with claim 10, wherein
one of said second liner-engaging projections is positioned in
closely spaced relation to and circumferentially intermediate of
each said adjacent pair of said first projections.
12. A composite closure in accordance with claim 10, wherein
each said first liner-engaging projection extends vertically
between generally opposed surfaces of said top wall portion and
said liner-retaining lip.
13. A composite closure in accordance with claim 10, wherein
each said first liner-engaging projection is substantially detached
from said liner-retaining lip.
14. A composite closure comprising:
a plastic cap having a top wall portion, a depending annular skirt
portion, and an annular liner-retaining lip extending inwardly of
said skirt portion in spaced relation to said top wall portion to
define an annular recess therewith; and
a plastic sealing liner positioned adjacent said top wall
portion,
said plastic cap including a plurality of circumferentially spaced
liner-engaging projections in engagement with said sealing liner,
said projections being positioned at least partially within said
annular recess and extending integrally generally from the junction
of said annular lip and said top wall portion inwardly of said
closure, each said liner-engaging projection has a free edge spaced
from and generally facing a surface of said annular lip which said
lip surface is generally opposed to said top wall portion.
15. A composite closure in accordance with claim 14, wherein
said liner-engaging projections are arranged in adjacent pairs,
wherein the projections of each said adjacent pair are arranged in
converging relation to each other to retain an edge portion of said
sealing liner therebetween.
16. A composite closure in accordance with claim 15, wherein
each said adjacent pair of liner-engaging projections converge at
an obtuse angle with respect to each other.
17. A composite closure in accordance with claim 14, wherein
said liner-engaging projections comprise first liner-engaging
projections, said plastic cap including a pluralty of
circumferentially spaced, second liner-engaging projections
extending integrally from said top wall portion in operative
association with said first projections for retaining said sealing
liner in position within said plastic cap.
18. A composite closure in accordance with claim 17, wherein
said first liner-engaging projections are arranged in adjacent
pairs, wherein the projections of each adjacent pair are arranged
in converging relation to each other, at least some of said second
liner-engaging projections are positioned in closely spaced
relation to and generally circumferentially intermediate of
respective ones of said adjacent pairs of said first projections.
Description
TECHNICAL FIELD
The present invention relates generally to closures for bottles and
like containers, and more particularly to a composite closure
including a plastic cap and a plastic sealing liner configured to
enhance mechanical retention of the liner within the plastic
cap.
BACKGROUND OF THE INVENTION
Commonly assigned U.S. Pat. Nos. 4,343,754, 4,378,893, 4,418,828,
4,407,422, and 4,497,765 disclose constructions for, and methods
and apparatuses for making, composite closures for bottles and like
containers. The closures are composite in the sense that they
include an outer plastic cap or shell, and a plastic sealing liner
positioned adjacent a top wall portion of the plastic cap for
effecting sealing engagement with an associated container. By such
a construction, the plastic material of the outer cap can be
selected to exhibit the requisite strength, while the material for
the inner sealing liner can be relatively soft for enhanced sealing
with the finish of a container. Significantly, composite closures
formed in accordance with the teachings of the above patents have
proven highly effective for use on containers having pressurized or
carbonated contents, with the above patents further disclosing
tamper-indicating closure pilfer band constructions for indicating
removal of a closure from a container. Portions of the above
patents not inconsistent with the present disclosure are hereby
incorporated by reference.
One aspect of the composite closure constructions of the above
patents which promotes effective sealing is the formation of the
sealing liner with a relatively thick annular sealing bead portion
which defines a generally inwardly facing sealing surface.
Formation is facilitated by molding the outer plastic cap with an
annular liner-retaining lip in closely spaced relation to the top
wall portion of the cap, with the annular lip desirably acting to
confine the material from which the liner is formed during in situ
formation of the liner, preferably in accordance with the
compression molding techniques disclosed in the above patents.
While the annular lip acts to retain the liner in position within
the cap after formation, liner retention is desirably enhanced by
the formation of liner-engaging projections integrally with the top
wall portion of the cap. In accordance with the teachings of U.S.
Pat. No. 4,407,422 and 4,497,765, formation of a plurality of
circumferentially spaced liner-engaging projections extending
integrally from the top wall portion in close association with the
annular liner-retaining lip desirably acts to mechanically retain
the peripheral edge portion of the sealing liner, thus retaining
the liner in position. Such circumferentially spaced liner-engaging
projections can be partially disposed within the annular recess
defined by the annular lip and the top wall portion, and are
preferably arranged to engage the relatively thick annular sealing
bead portion of the liner.
While the above-described sealing construction has proven effective
for use on containers having carbonated contents, experience has
shown that enhanced liner retention can be desirable for some
applications. As will be appreciated, the liner of a closure is
subjected to torsional stresses attendant to application to,
removal from, and re-application to a container, and it is
generally desirable to avoid dislodgement of the liner when it is
subjected to such stresses. While the above-described arrangement
of circumferentially spaced liner-engaging projections provides
highly effective liner retention with many liner materials, such
materials can vary in hardness and like physical characteristics,
thus affecting the liner retention characteristics of the
liner-engaging projections and annular lip. While increasing the
dimensions of the circumferentially spaced liner-engaging
projections can act to enhance liner retention, it is desirable
that the projections not be so large as to interfere with
distribution of the liner material during liner formation, or
extend through the liner material after the liner is formed.
Accordingly, the present invention concerns an improved liner
retaining construction for a composite closure including a plastic
cap and a plastic sealing liner.
SUMMARY OF THE INVENTION
In accordance with the present invention, a composite closure is
disclosed which includes an outer plastic cap and an inner plastic
sealing liner. The plastic cap of the closure is preferably of the
above-described type, and includes an annular liner-retaining lip
in closely spaced relation to a top wall portion of the cap thereby
defining an annular recess therewith. Significantly, the closure
cap further includes a plurality of integral liner-engaging
projections at least partially disposed in the annular recess of
the cap, and which extend inwardly from the junction of the annular
lip and the top wall portion. The projections are preferably
arranged in adjacent pairs which are in converging relation to each
other. Each closely spaced adjacent pair of projections is thus
arranged in a "dovetail" configuration for mechanically entrapping
and confining an annular edge portion of the associated sealing
liner between the adjacent pair of projections, and thus effects a
liner gripping action in a generally radial direction relative to
the axis of the closure.
The outer plastic cap of the present closure includes a top wall
portion, and an integral depending annular skirt portion which is
preferably provided with an integral internal thread formation for
coaction with a like thread formation on the neck of an associated
container. The plastic cap can be formed with an integral
tamper-indicating pilfer band if desired.
The plastic cap further includes an inwardly extending, annular
liner-retaining lip which extends inwardly from the skirt portion
of the cap in closely spaced relation to the top wall portion, and
thus defines an annular recess with the top wall portion. The
present closure further includes a plastic sealing liner positioned
adjacent the top wall portion of the closure cap for effecting
sealing engagement with an associated container. The sealing liner
preferably includes a relatively thick annular sealing bead portion
which extends into the annular recess of the closure cap, and which
preferably defines a generally inwardly facing sealing surface.
In accordance with the present invention, the plastic cap of the
closure includes a plurality of circumferentially spaced
liner-engaging projections positioned at least partially within the
annular recess of the plastic cap, with the projections extending
integrally inwardly from the junction of the annular lip and the
top wall portion of the closure. In one disclosed embodiment, these
projections are generally web-like in configuration, and extend
vertically between generally opposed surfaces of the annular lip
and the top wall portion. In another embodiment, the projections
are detached from the annular lip, and thus each projection has a
free edge spaced from and generally facing a surface of the annular
lip which is generally opposed to the top wall portion.
Significantly, all of the liner-engaging projections are preferably
arranged in adjacent pairs, wherein the projections of each
adjacent pair are arranged in converging relation to each other. By
this construction, an edge portion of the sealing liner is confined
between each pair of the converging projections, thus providing
highly effective retention of the sealing liner in position within
the plastic cap adjacent the top wall portion.
In the presently preferred form, the above-described converging
pairs of liner-engaging projections comprise first liner-engaging
projections, with the plastic cap further including a plurality of
circumferentially spaced second liner-engaging projections
extending integrally from the top wall portion of the cap in
operative association with the first projections. The second
projections are preferably arranged to engage the relatively thick
annular sealing bead portion of the sealing liner, and are
positioned in close association with the annular lip of the closure
cap. The second liner-engaging projections can be partially or
completely disposed within the annular recess of the cap. In the
preferred form, at least some of the second projections are
arranged in closely-spaced relation to and generally
circumferentially intermediate of respective adjacent pairs of the
converging first projections, thus cooperating with the first
projections for further enhancing the liner retention
characteristics of the construction.
The desired liner-retention characteristics of the present closure
are enhanced by configuring the converging surfaces of each pair of
first projections to be non-radial with respect to the closure,
i.e., each first projection is arranged at an acute angle to a line
tangential to the base of the projection and the closure.
Other features of the present invention will become readily
apparent from the following detailed description, the accompanying
drawings, and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan view of a composite closure embodying the
principles of the present invention, with portions of the closure
shown in cut away and cross-section;
FIG. 2 is a cross-sectional view of the present closure taken
generally along line 2--2 of FIG. 1;
FIG. 3 is an enlarged perspective view illustrating the
configuration of the outer plastic cap of the present closure for
effecting liner retention;
FIG. 4 is a fragmentary view in partial cutaway similar to FIG. 1
illustrating an alternate embodiment of the present invention;
and
FIG. 5 is an enlarged perspective view similar to FIG. 3 further
illustrating the alternate embodiment of the present invention
shown in FIG. 4.
DETAILED DESCRIPTION
While the present invention is susceptible of embodiment in various
forms, there is shown in the drawings and will hereinafter be
described first and second alternate embodiments thereof, with the
understanding that the present disclosure is to be considered as an
exemplification of the invention, and is not intended to limit the
invention to the specific embodiments illustrated.
With reference first to FIGS. 1-3, therein is illustrated a first
embodiment of a composite closure 10 embodying the principles of
the present invention. Closure 10 includes a cup-like plastic
closure cap or shell 12 having a top wall portion 14 and a
generally cylindrical, depending annular skirt portion 16 integral
with top wall portion 14. An internal thread formation 18 is
provided on the inside of skirt portion 16, and is adapted to
cooperate with a like thread formation on a container to which the
closure is applied. The exterior of the skirt portion 16 is
preferably provided with a plurality of circumferentially spaced
finger ribs 20 to facilitate manipulation of the closure. Cap 12 is
preferably made of moldable thermoplastic, such a polypropelyene or
polyethylene. Formation of cap 12 can be very efficiently effected
by compression molding techniques in accordance with the teachings
of U.S. Pat. Nos. 4,343,754 and 4,497,765, but a closure embodying
the principles disclosed herein can be otherwise formed.
Closure 10 is of the so-called composite type, and includes a
plastic sealing liner 24 disposed adjacent top wall portion 14.
Liner 24 (shown partially cut away in FIGS. 1 and 3) includes a
disk-shaped central portion 26, and a relatively thick annular
sealing bead portion 28. The annular sealing bead portion 28 is
configured to define a generally inwardly facing sealing surface
(shown as comprising adjacent generally cylindrical and
frusto-conical surfaces), with the liner 24 thus arranged to effect
a so-called "top/side seal" with an associated container. Liner 24
is preferably made of moldable thermoplastic, such as
polyvinylchloride (PVC).
Secure retention of sealing liner 24 within cap 12 promotes proper
sealing of a container to which the closure is fitted. To this end,
cap 12 is formed with an annular liner-retaining lip 30 extending
integrally inwardly from skirt portion 16. Annular lip 30 is
positioned in closely spaced relation to top wall portion 14, and
thus defines an annular recess 32 within which at least a portion
of bead portion 28 of liner 24 is positioned. A plurality of
circumferentially spaced reinforcing gussets 34 can be provided
extending integrally between skirt portion 16 and lip 30 for
reinforcing the lip. Annular lip 30 not only acts to retain sealing
liner 24 in position within cap 12, but further promotes in situ
formation of liner 24, such as by compression molding of the liner,
by confining the moldable liner material during liner
formation.
Closure 10 is illustrated as including a pilfer band 38 which may
be optionally formed integrally with cap 12. Pilfer band 38
includes an annular band portion 40, and a plurality of
circumferentially spaced, relatively flexible wings or projections
42 integral with band portion 40. Wings 42 are adapted to coact
with an annular locking ring typically provided on the neck of the
container to resist removal of the closure from the container, and
thereby at least partially detaching pilfer band 38 from skirt
portion 16 for indicating closure removal. A fracturable connection
between the pilfer band 38 and the skirt portion 16 can be very
efficiently formed by the provision of circumferentially spaced
ribs 44 which extend between the inside surfaces of band portion 40
and skirt portion 16. The fracturable connection is further
provided by partially or completely circumferentially scoring the
closure at 46, thereby distinguishing the pilfer band from the
skirt portion and preferably partially cutting the ribs 44 whereby
the ribs are frangible for detachably joining the pilfer band to
the skirt portion. A closure including a pilfer band as illustrated
can be formed in accordance with the teachings of U.S. Pat. Nos.
4,418,828 and 4,497,765.
In accordance with the present invention, secure retention of the
sealing liner 24 within plastic cap 12 is enhanced by the provision
of a plurality of circumferentially spaced, first liner-engaging
projections 48 positioned within the annular recess 32 of the
closure cap 12. Projections 48 are each of a generally web-like
configuration, and extend integrally inwardly of the closure
generally from the junction of annular lip 30 with top wall portion
14. For purposes of the present disclosure, the junction of annular
lip 30 and top wall portion 14 can be considered to be that region
of the closure cap where annular recess 32 has its maximum internal
diameter. As illustrated, the projections 48 extend vertically
generally between the top wall portion and the annular lip, and
thus, the free edges of projections 48 are spaced from the inner
edge of annular lip 30 where the lip 30 merges into and joins top
wall portion 14.
Significantly, all of the liner-engaging projections 48 are
preferably arranged in adjacent pairs wherein the projections of
each adjacent pair are arranged in converging relation to each
other whereby they cooperate to mechanically entrap and confine an
edge portion 49 of annular sealing bead 28 of sealing liner 24. By
this converging configuration of the projections 48, a
"dovetail"-like region is defined between each adjacent pair, with
portions 49 (FIG. 3) of liner 24 between adjacent pairs of
projections 48 likewise having such a dovetail configuration
attendant to in situ formation of the liner. By this arrangement,
it will be noted that each projection 48 is arranged in diverging
relation to the adjacent projection 48 of the immediately adjacent
converging pair of projections.
In a current embodiment of the present closure wherein annular
recess 32 has a maximum internal diameter of approximately 1.07
inches, adjacent pairs of projections 48 have been provided at 30
degree intervals about the circumference of closure cap 12. Each
projection 48 has been formed with a thickness dimension at "a"
(FIG. 1) on the order of 0.013 inches, and a maximum length
dimension at "b" on the order of 0.035 inches. Spacing between
converging projections of each adjacent pair has been provided, on
average, at 0.074 inches, as shown at "c" in FIG. 1. Thus, the
projections 48 of each adjacent pair are sufficiently closely
spaced to mechanically confine the respective liner edge portion 49
therebetween, even though the liner material may be relatively
deformable. Thus, a radially-acting gripping action on the liner 24
is effected for secure retention of the liner in position within
the closure cap.
The projections 48 of each adjacent pair are arranged to converge
at an obtuse angle preferably in the range of 100-130 degrees, with
this angle being indicated at "alpha" in FIG. 1, and in a current
embodiment being on the order of 120 degrees. Each projection 48
extends non-radially inwardly of closure cap 12, with each
projection 48 preferably arranged at an acute angle of
approximately 30-45 degress with respect to a line tangential to
the base of the projection and the closure cap; this acute angle is
shown at "beta" in FIG. 1, and in a current embodiment is on the
order of 38 degrees.
It is preferred that a certain relationship be established between
the spacing of the converging projections 48, and the dimension of
the liner edge portion 49 confined thereby. In this illustrated
embodiment, the maximum chordal dimension "x" of the portion 49
(see FIG. 1) confined by a pair of projections 48 is on average
0.110 inches, while the spacing between the inner portions of the
projections at "c" is on average 0.074 inches, as noted. Thus, the
degree of liner-gripping interference created between the
projections and the edge portion of the liner can be calculated
as:
Since the liner material is relatively soft and deformable, values
for the above-described interference greater than 0.35 are
presently preferred to inhibit dislocation of the liner 24.
While the provision of liner-engaging projections 48 in adjacent
converging pairs provides highly effective retention of sealing
liner 24 within plactic cap 12, it is presently preferred to
further enhance the liner retention characteristics of the closure
by providing a plurality of second liner-engaging projections 50 in
operative association with the first converging pairs of
projections 48. Second projections 50 extend integrally from top
wall portion 14, and in a current embodiment, have been provided at
10 degree intervals about the circumference of closure cap 12, with
each projection 50 being generally cylindrical and having a
diameter on the order of 0.012-0.016 inches, and a height of
approximately 0.025-0.030 inches.
In the preferred form, the second projections 50 are arranged with
respect to the converging pairs of first projections 48 such that
one of the projections 50 is provided in closely spaced relation to
and generally circumferentially intermediate of each converging
pair of projections 48. In the above-described current embodiment,
the spacing between the projection 50 provided circumferentially
intermediate of an adjacent pair of projections 48 is on the order
of 0.012 inches as illustrated at "d" in FIG. 1. This arrangement
of projections 48 and 50 not only arranges the projections for
cooperation for enhancing liner retention, but further provides
sufficient spacing between the projections 48 and the projections
50 to facilitate fabrication of suitable molding tooling without
compromising the structural integrity of the tooling.
Referring now to FIGS. 4 and 5, therein is illustrated a composite
closure configured in accordance with an alternate embodiment of
the present invention. In most respects, this alternate embodiment
is configured in accordance with the previously described
embodiment, and thus like reference numerals have been employed.
However, it will be observed that in this alternate embodiment, a
plurality of first liner-engaging projections 58 are provided which
generally correspond in function to previously-described
projections 48, but with the projections 58 being differently
configured than projections 48.
More specifically, projections 58 are preferably arranged such that
each adjacent pair of the projections 58 are disposed in converging
relation to each other. By this arrangement, a "dovetail"-like edge
portion 59 of sealing liner 24 is disposed between and retained by
each converging pair of the projections 58. As in the previously
described embodiment, it is presently preferred that first
liner-engaging projections 58 be provided for cooperation with a
plurality of circumferentially spaced second liner-engaging
projections 50, with at least some of the projections 50 positioned
in closely spaced relation to and generally circumferentially
intermediate of respective ones of adjacent pairs of the first
projections 58.
As best illustrated in FIG. 5, it will be observed that while
projections 58 extend inwardly of closure cap 12 generally from the
junction of annular lip 30 and top wall portion 14, each of the
projections 58 is substantially detached from the annular lip 30.
Thus, each projection 58 includes a free edge portion which is
spaced from and generally faces a surface of lip 30, which said lip
surface is generally opposed to top wall portion 14 of closure cap
12.
While projections 58 are intended to effect mechanical retention of
an edge portion of sealing liner 24, the manner in which the
projections 58 are detached from annular lip 30 facilitates closure
manufacture. Specifically, previously-described projections 48,
which extend vertically between top wall portion 14 and annular lip
30, to a certain extent act to reinforce and rigidify the annular
lip 30, and inhibit flexible movement of the lip 30 in a direction
away from top wall portion 14. Such flexible movement of annular
lip 30 can be desirable for facilitating removal of closure cap 12
from the male forming plunger with which the cap is formed.
Experience has shown that in the event that operation of the
apparatus with which closure cap 12 is molded is temporarily
interrupted, the plastic material from which the cap is formed can
solidify to such an extent that the annular lip 30 cannot be
readily deformed a sufficient amount to permit the preferred
"stripping" of the closure cap from the male forming plunger.
Again, it is believed that the rigidifying effect of
previously-described projections 48 exacerbates this phenomenon,
and thus, projections 58 of the embodiment of FIGS. 4 and 5 are
detached from annular lip 30 to provide the annular lip with
desired flexibility in a direction away from top wall portion
14.
In a current embodiment, projections 58 have been arranged to
converge at an obtuse angle preferably in the range of 100-130
degrees, (such as indicated at "alpha" in FIG. 1 of the previous
embodiment). Each projection 58 extends non-radially inwardly of
closure cap 12, with each projection 58 preferably arranged at an
acute angle of approximately 30-45 degrees with respect to a line
tangential to the base of the projection and the closure cap (such
as illustrated at "beta" in FIG. 1 of the previous embodiment).
Projections 58 are preferably provided with a thickness generally
on the order of the thickness of previously described projections
48, i.e., on the order of 0.013 inches (note dimension "a" in FIG.
1 of the previous embodiment). However, projections 58 are
preferably provided with a substantially greater maximum length
dimension as illustrated at "e" in FIG. 5, such as on the order of
0.065 inches. Spacing between converging projections 58 of each
adjacent pair has been provided on the order of 0.050 inches, as
shown at "f" in FIG. 4.
As best illustrated in FIG. 5, the free edge of each projection 58
in a current embodiment has been formed as generally straight, and
is arranged at an acute angle to the surface of top wall portion
14, wherein this angle "gamma" is on the order of 20 degrees.
However, it is to be understood that the precise configuration of
the projections 58 can be varied in accordance with the teachings
herein. The exact shape of the projections in part depends upon the
machining technique employed for forming suitable slots in a male
molding plunger with which the closure cap is formed, with
projections 58 formed in such slots.
From the foregoing, it will be observed that numerous modifications
and variations can be effected without departing from the true
spirit and scope of the novel concept of the present invention. It
is to be understood that no limitation with respect to the specific
embodiments disclosed herein is intended or should be inferred. It
is, of course, intended to cover by the appended claims all such
modifications as fall within the scope of the claims.
* * * * *